ASGI app misses coverage lines after awaiting async sqlalchemy code · Issue #1082 · nedbat/coveragepy (original) (raw)
Describe the bug
This may be a very specialized problem, but since it concerns very widely used libraries I thought it would be helpful to report:
Within an ASGI app (the example uses starlette here), using the new async/await engine in sqlalchemy results in any lines AFTER usage of the database engine not being recognized in coverage.
To Reproduce
How can we reproduce the problem? Please be specific. Don't just link to a failing CI job. Answer the questions below:
What version of Python are you using?:
3.8.5 (virtual environment using conda)
What version of coverage.py are you using? The output of coverage debug sys is helpful.
-- sys -------------------------------------------------------
version: 5.3
coverage: /home/user/env/lib/python3.8/site-packages/coverage/__init__.py
tracer: -none-
CTracer: available
plugins.file_tracers: -none-
plugins.configurers: -none-
plugins.context_switchers: -none-
configs_attempted: .coveragerc
setup.cfg
tox.ini
pyproject.toml
configs_read: /home/backend/pyproject.toml
config_file: /home/backend/pyproject.toml
config_contents: b'[tool.coverage.report]\nshow_missing = true\n'
data_file: -none-
python: 3.8.5 (default, Sep 4 2020, 07:30:14) [GCC 7.3.0]
platform: Linux-5.4.0-56-generic-x86_64-with-glibc2.10
implementation: CPython
executable: /home/user/env/bin/python
def_encoding: utf-8
fs_encoding: utf-8
pid: 2488889
cwd: /home/user/backend
path: /home/user/env/bin
/home/user/env/lib/python38.zip
/home/user/env/lib/python3.8
/home/user/env/lib/python3.8/lib-dynload
/home/user/.local/lib/python3.8/site-packages
/home/user/env/lib/python3.8/site-packages
environment: CONDA_PYTHON_EXE = /home/user/anaconda/bin/python
command_line: /home/user/env/bin/coverage debug sys
sqlite3_version: 2.6.0
sqlite3_sqlite_version: 3.33.0
sqlite3_temp_store: 0
sqlite3_compile_options: COMPILER=gcc-7.3.0
ENABLE_COLUMN_METADATA
ENABLE_DBSTAT_VTAB
ENABLE_FTS3
ENABLE_FTS3_TOKENIZER
ENABLE_FTS4
ENABLE_FTS5
ENABLE_GEOPOLY
ENABLE_JSON1
ENABLE_RTREE
ENABLE_UNLOCK_NOTIFY
MAX_DEFAULT_PAGE_SIZE=32768
MAX_EXPR_DEPTH=10000
MAX_VARIABLE_NUMBER=250000
SECURE_DELETE
THREADSAFE=1
What versions of what packages do you have installed? The output of pip freeze is helpful.
starlette==0.13.6
sqlalchemy==0.14.0b1
coverage==5.3
What code are you running? Give us a specific commit of a specific repo that we can check out.
Given the packages above, the code should run "as is":
What commands did you run?
https://gist.github.com/daviskirk/7e8495ca5b8150f9002c5bc80630fa5a#file-run-sh
Expected behavior
I expect all lines to be covered, since all lines were run (acording to the output (see the printed result) and setting breakpoints).
Instead, the lines following the database operations are skipped:
Additional context
- Note that the sqlalchemy version is in beta, but since it is very widely used I expect this to be a problem for many people.
- Sqlalchemy uses the "greenlets" library to pass through context. I can guess that this might have something to do with the missing coverage? However, normal applications (mine included) using starlette or fastapi (or most of the other asgi frameworks), can't switch to the
--coverage "greenlet"version since all wsgi endpoints run in a thread (and then none of those are covered). - I have no problem concluding that this isn't coverages problem ;), if that is indeed the case. But I wanted to document it for anyone else running into the issue (or perhaps a solution if one does exist).